Breast cancer is the second leading cause of cancer-related deaths in women of the Western world. In the U.S.A. alone, over 180,000 new cases of breast cancer are diagnosed each year. Of these patients, approximately 25% will die despite aggressive diagnostic and therapeutic intervention. Despite the considerable and recent improvement in breast cancer diagnostics and therapy, the morbidity and mortality associated with this disease remain alarming.
The best chance for survival of breast cancer is to detect the cancer before it has had a chance to metastasize. Unfortunately, breast cancer can reappear and metastasis can occur even if the cancer was confined to the breast at the time of detection. Once metastatic breast cancer has been diagnosed, it can be treated. However, in most cases, none of the treatments lead to long-term survival.
One of the pathways for breast cancer systemic metastasis involves the passage of cancer cells through the lymphatic system. There is convincing experimental support for a metastatic breast cancer model that has an early state, in which the breast cancer cells are confined to the breast and the regional lymph nodes, and have not yet metastasized to distant sites. Additional recent preclinical and clinical immunohistochemical, physiologic, and pathophysiologic metastatic breast cancer studies support a model of breast cancer metastasis where the breast cancer cells first invade peritumoral lymphatics, then spread to locoregional lymph nodes, prior to hematogenous metastasis in a subject.